A pulse shaping technique for spur suppression in injection-locked synthesizers

Abstract

Frequency synthesizers based on sub-harmonic injection- locked oscillators can reduce power and area effectively. However, they suffer from unwanted side-bands caused by undesirable harmonics in the injection pulse. This paper presents a pulse shaping technique that reduces these undesirable harmonics in the injection pulse and produces low-spur synthesized output. The robustness of the proposed technique and the impact of circuit non-idealities are also discussed in depth. A test chip tailored to the first band group of WiMedia UWB is fabricated in 0.13- m CMOS technology to verify the effectiveness of this technique. Experimental results show that the proposed pulse shaping attenuates the spurs by 22 dB and suppresses them below 47 dBc. The prototype achieves a switching time of less than 4.7 ns and phase noise of 122 dBc/Hz@1 MHz offset at 4.488 GHz. The chip occupies an active area of 0.15 mm and draws only 18 mA from a 1.2-V supply. © 2012 IEEE.